Currently it is necessary in many therapeutic applications involving animals or humans in the field of cellular biology to make use of reservoirs capable of conserving, concentrating or distributing at a controlled rate, in vitro and/or in vivo, one or several active substances, and if the need arises, the creation in situ of a new product.
Equally needed are chambers for conservation and/or for cultures in vitro and/or in vivo of cells, living and dead, of bacteria, of viruses, etc.
These reservoirs are designed to play, in some cases, the role of a simple container, or of containers having active walls, in place of implants, and the desired functions according to its form and its biodegradability may be diverse. Finally in a more general fashion, the reservoirs must be able to play the part of captivating or transmitting a very complex regulating system to liberate one or several active substances (biocapture or bioreactor). See Biofutur, January 1984, Biofutur, S. A., Ed. 75007, Paris.
Containers made out of implantable plastic material are already known, especially those of the type "micro-pump" which permit passage through an organism at a controlled rate, of determined doses of an active substance. It is necessary to note that in all cases, these containers are only somewhat biocompatible, and are not biodegradable.
It has also been established (Huc, A. and Comte, Ph., 1983, Biofutur, No. 9, pp 53-55) that collagen is the substance of choice for the preparation of biomaterials. The protein which constitutes a support matrix for conjunctive tissue, also possesses remarkable mechanical properties, an excellent biocompatibility, and a biogradability which is optionally modifiable according to the particular goal that is desired.
The collagen molecule having a length of about 3000 .ANG. and a width of about 15 .ANG. is constituted by three peptide chains. Each chain has a mass of about 100,000 daltons, and is in helicoidal form. The axes of the helices extend helically around a common axis through the interior of the macromolecule. Between certain chains, there exist reticulated or cross-linked bonds. The ordered arrangement of the macromolecules between these peptide chains leads to formation of fibers.
The excellent mechanical properties of collagen are provided in large part, by the helicoidal structure and the reticulated bonds.
The antigenic character of collagen is also very low. Consequently, collagen originally from an animal does not provoke an action of rejection when applied in vivo to a human being, according to a study conducted by Takeda, U. et al. and appearing in the Journal of Toxicology Sciences, Vol. 7, Suppl. II, pp 63-91, (1982).
It is also possible to modify the permeability of a collagen membrane by a variety of treatments (Stenzel, K. H. et al., American Rev. Biophys. and Bioeng., Vol. 3, pp 231-253, 1954).